November 27, 1914] 



SCIENCE 



789 



is composed of dune sand, probably derived 

 from the Loup Fork (Tertiary) beds. These 

 hills seem to have been formed largely at some 

 previous epoch and to have become stabilized 

 and occupied by vegetation. Through the in- 

 fluence of man, mostly on account of prairie 

 fires and overgrazing, many of these ancient 

 dunes have become rejuvenated to the detri- 

 ment of those responsible for it. 



After giving the results of his careful meas- 

 urements of wind, rainfall, evaporation, tem- 

 perature and other ecological factors, Professor 

 Pool takes up in detail the vegetation of the 

 region. It is a pleasure to note the author's 

 caution in using the word " formation." He 

 rightly believes in using this term only for 

 large units, referring the " formations " of 

 many authors to associations. The character- 

 istic upland formation is the prairie-grass 

 formation, which is contrasted sharply with 

 the short-grass formation of the plains, the 

 two embracing most of the great climatic 

 grasslands between our eastern forests and the 

 mountains. These two great formations have 

 similar physiognomy, but different component 

 species; the limiting factors are the available 

 water and competition, and not temperature, 

 as supposed by Merriam. The chief associa- 

 tion is the bunch-grass association, dominated 

 especially by Andropogon scoparius; this is 

 the vegetation that prevailed generally before 

 the advent of the white man, and is regarded 

 as the temporary climax of the region. The 

 vegetation of this association is open, the 

 grasses occurring in tufts or bunches, but it is 

 supposed that ultimately some closed prairie- 

 grass association will prevail. There is evi- 

 dence of this in the spear grass association 

 (dominated by 8tipa comaia and Koeleria 

 cristata), and farther west in the grama- 

 buffalo grass association (dominated by Boute- 

 loua and BuTbilis). 



Doubtless the most interesting features of 

 the sand hills are the blow-outs. These are 

 retrogressive features and are due, as noted 

 above, especially to prairie fires and over- 

 grazing. At first through the death of the 

 plants there are small patches of bare sand. 

 Later the sand is scooped out by the wind. 



forming conical or crateriform depressions, 

 knovm as blow-outs. As the sand is scooped 

 out, more sand falls in from the sides, so that 

 the blow-out is increased in circumference, as 

 well as in depth. Extreme cases are recorded 

 where the depth may be as much as 100 

 feet and the circumference 600 feet. When 

 wind erosion becomes checked, vegetation 

 again gets a foothold, the chief pioneers being 

 Redfieldia fiexuosa, Psoralea lanceolata and 

 Oalamovilfa longifolia. After a time these 

 pioneers are followed by the bunch-grass asso- 

 ciation; after this vegetational changes are 

 much less rapid. One of the chief features 

 of interest in the woodland formations along 

 the streams is the overlap of the deciduous 

 eastern forest and the yellow pine (Pinus 

 ponderosa scopulorum) forest of the west. The 

 lowland formations are much like those else- 

 where, as to both content and succession, 

 except that a meadow type represents the 

 temporary climax; probably one of the more 

 eastern of the prairie grass associations repre- 

 sents a more ultimate condition. 



Professor Pool is to be congratulated on his 

 thorough and sane treatment of his problem. 

 His contribution is solid and satisfying, and 

 is a pleasant contrast to the many ephemeral 

 disquisitions which even yet masquerade too 

 frequently under the name of ecology. 



H. C. COWLES 



SPECIAL ABTICLMS 



THE EFFECTS OF SMALL REPEATED INTRAPERITO- 

 NEAL INJECTIONS OF WITTe's PEPTONE 

 SOLUTIONS IN GUINEA-PIGS^ 



The experiments reported in this prelimi- 

 nary paper form a group in a series which has 

 been planned to determine the organic effects 

 of parenteral introduction of certain substances 

 which may be produced within the tissues of 

 an organism, or which may be absorbed from 

 the gastro-intestinal tract. The fact that 

 Longcope^ has reported that parenteral diges- 



1 From the laboratories of the Cincinnati Gen- 

 eral Hospital and the department of pathology of 

 the University of Cincinnati. 



2 Longcope, Jmr. Exp. Med., 1913 (18), 678. 



